A domain protection method of DC traction feeder segment

The deficiency of the metro direct-current feeder protection is mainly attributed to the application of single-ended current as the sole method in the detection and identification of breakdowns, which is time-consuming in case of remote short circuit and is very likely to fail or make mistakes. Therefore, by evaluating the distribution relationship between the side currents and line or load current, this paper proposes a segment domain protection method. Through this method, the protection measurement data at both sides of independent feed segment can be shared synchronously via optical fiber, and brand new protection criteria can be realized after a comprehensive domain processing. This paper presents the composition principles of independent feeder section and consequently proposes the "sum current" protection principle utilizing the sum of two ends’ currents, impedance protection principle and double-ended tripping protection principle. In the end, approaches to realizing those protection principles are provided. The method can realize the entire DC feeder quick-action, which improves the speed, sensitivity and reliability of the Metro direct-current feeder protection.